This is a proposal to conduct a population-based, case-control study of penile and urethral cancer in thirteen counties of western Washington in order to test the hypothesis that infection with one or more sexually transmitted viruses is related to an increased risk of these cancers. All men aged 16-79 who were diagnosed as having penile or urethral cancer during the period January, 1979 through December 31, 1988 will be identified and recruited into the study. In addition, all women diagnosed as having urethral cancer will be included. Cases and controls will be interviewed regarding a history of sexually transmitted diseases. For each case, two persons from the population of these counties will be selected as controls using random digit dialing. Blood and tissue samples will be collected for all cases. Blood samples will be collected from one of the two interviewed matched controls. Urethral and penile tissue specimens obtained from an unselected group of persons undergoing autopsy will be collected as a tissue comparison. We will investigate past viral infection in several ways: (a) history of clinical infection; (b) examination of tissue samples using in situ hybridization tests; and (c) examination of serum for antiviral antibodies.